The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
The wheels of tractors and trailers are supported on stationary, transverse axles attached to suspension components of the tractor or trailer which are, in turn, attached to the vehicle frame. As such, the axles represent the interface between the rotating tire and wheel assemblies and the stationary structure of the vehicle. To reduce friction and extend the service life of the interface components, roller bearing assemblies are utilized in pairs on a stepped terminal portion of the axle at each wheel location. Generally speaking, a larger diameter roller bearing assembly is disposed on an inner, larger diameter bearing surface of the axle and a smaller diameter roller bearing assembly is disposed on an outer, smaller diameter bearing surface.
Although well designed, given that many tractors, trailers, other long haul vehicles and delivery trucks log one hundred thousand miles of service per year or more, it is not surprising that these bearing assemblies and the axles upon which they rotate are subject to failure. Such failures are seldom predictable and they are therefore not especially amenable to preventative maintenance. Hence, the failure will frequently occur at some distance from a truck terminal or a qualified repair shop.
In response to this problem, certain procedures have been developed to facilitate repair of tractor, trailer and long haul vehicle axles at the failure site. One of these is presented in U.S. Pat. No. 4,098,029. Here, weld material is built up on worn or damaged bearing surfaces and then ground down to achieve a coaxial, round bearing surface. Another approach is presented in U.S. Pat. No. 4,455,732. Here, an apparatus and method are taught which are directed to boring a concentric opening in the end of an axle into which is installed a replacement axle stub which is then welded in place.
My U.S. Pat. No. 6,024,418 illustrates a more recent improvement in axle repair. In this repair method, a long spindle having both inner and outer bearing surfaces and threads is utilized with a sleeve or liner. After the damaged end of the axle has been removed, the spindle and liner are installed in the axle and welded at several locations away from regions of high stress.
After an axle repair is complete, it is generally necessary to lubricate the ball bearing assemblies installed on the inner and outer bearing surfaces. One way this has been achieved when the repair involves a tractor axle involves lifting the side of the tractor opposite the repair location so that a small portion of the gear lubricant in the differential flows down the axle to the bearings to lubricate them. While satisfactory from a lubrication standpoint, the design of the spindle may be such that it inhibits such lubricant flow unless the tractor is tilted to an unacceptably large angle. Accordingly, there is a need for an improved spindle configuration that facilitates tractor axle bearing lubrication through the just described process.
Additionally, while the replacement spindle utilized in this method is strong and exhibits a large factor of safety, the replacement spindle and sleeve may weigh forty pounds or more. If, as is often the case, all four spindles of a trailer are replaced at the same time, the added weight, i.e., taking into account the weight of the removed, damaged axle portion, may still total approximately one hundred pounds. Thus, there is also a need to provide a lower weight spindle replacement which provides the necessary strength and desired factor of safety.